Process of preparing pure lithum compounds.



, Lithium Compounds, of which the fo UNITED STATES PATENT OFFICE.

WALTER E. WADMAN, OF BAYONNE, NEW JERSEY, ASSIGNOR TO HYGIENIC CHEMICAL COMPANY OF NEW JERSEY, A CORPORATION OF NEW JERSEY.

PROCESS OF PREPARING PETRE LITHIUM COMPOUNDS.

To all whom it may concern:

Be it known that I, WALTER E. WADMAN, a subject of the United Kingdom of Great Britain and Ireland, and resident of Bayonne, in the county of Hudson and State of New Jersey, have invented a new and useful Improvement in Process of Preparirn Pure Ilowing is a specification.

My invention relates to an improvement in process forseparating and purifying lithia sulfate.

In the manufacture of lithia salts by treatin aluminous or other minerals with sulfuric acid, and particularly such minerals as also contain potash, thereis obtained ultimately a solution consisting essentially of a mixture of the sulfates of lithia and potash.

It is well known thatin the presence of other alkali sulfates 'the precipitation of lithia carbonate is very incomplete, owing to the solubility of litia carbonate in solutions of alkali sulfates. Therefore, if it be attempted to produce lithia carbonate from a solution of mixedlith-ia and potash sulfate, much of the lithia carbonate remains dissolved in the mother liquors and is either lost or is only recoverable by tedious andexpensive methodsx' In such cases the loss is the greater the more alkaline sulfate there is present and it is therefore very desirable to separate the lithia sulfate as completelyas possible from the potash sulfate before'precipitating. the lithia as carbonate. Such separation cannot be efficiently accomplished by the usual methods of crystallization, owing to the formation of a double sulfate of lithia and potash 4 Now I have discovered that. it is possible to effect a practically complete separation of sulfate of lithia from sulfate 'of potash when the same occur togpther, by taking advanof ad tageof the insolubi ty of sulfate of potash in ammonia and the solubility of sulfate of lithia in the same mens'truum. Thus, for example, when, to a solution containing sulfate otash and sulfate of lithia, ammonia is or passed in as a gas, the sul ate of potash is precipitated as afine crystalline powder,-

eavi the lithia in solution. The precipitatlon'o sulfate of potash is more or less complete depend ng on the strength of the solutions and the amount of ammonia. added lthereto.

Specification of Letters Patent.

Application filed October 17. 1906- Serial No. 339.282.

ed, either as a strong a ueous solution,

Patented Jan. 14, 1908.

If a saturated solution of the mixed sulfates be used and ammonia gas passed in u to the point of saturation, the separation w' 1 be practically complete, and by careful manipulation 97% or more of all the potash present can be separated. In order to obtain as complete a separation as possible it is preferable to use ammonia gas, although a partial separation can be effected by aqueous ammonia.

The invention is applicable to all solutions containing sulfate of lithia in admixture with sulfate of potash, whether obtained by direct treatment of lithia ores with sulfuric acid, or by the process of treatingthe ores with sulfate of potash described and claimed by me in application for Letters Patent of the United States No. 316,231, or to the mother liquors left after precipitating lithia carbonate from lithia 'sulfate by means of potash carbonate, or to mixed'solutions of lithia and potash sulfates howsoever obtained.

To the strong solution of the mixed sulfates I either add a suitable amount of aqueous ammonia, or pass into the solution, ammonia gas, the last method being preferable.

If gas is used the solution must be kept cool by means of a cooling coil, water-jacket or other means to make the absorption of ammonia as complete as possible.

The crystalline preci itate of potash sulfate is easily removable from the ammoniacal solution .of lithia sulfate, by filtration or other suitable means, and the ammonia can then be driven off by'heat and applied to the treatment of a fresh lot of the mixed solutions. y g

' The solution left after driving off the am monia is practically a ure solution of lithia sulfate; from which litiiia carbonate may be precipitated with a minimum of loss due to the solubility of lithia carbonate in alkaline sulfate solutions.

I claim as my invention:

1. The recess of preparing pure lithium compoun s from solutions containing a mixture of lithia sulfate and potash sulfate, consisting in adding thereto ammonia in an amount sufficient to render the potash sulfate insoluble, then removing the same from the liquid, then removing the ammonia, and finally precipitating the lithia from'the solution in the form of a carbonate.

2, In a process of preparing pure compounds from solutions containing a mixlithium ture of lithia s ulfate and potash'sulfate, the

improvement which consists in adding thereto ammonia in an amount sufficient to render the potash sulfate insoluble. Y I 3. In a process of preparing pure lithium compounds from solutions containing a mixture of lithia sulfate and potash sulfate, the

improvement which consists in adding thereto ammonia in an'amount sufiicient to rencipitating t of lithia sulfate and potash sulfate, 7

the improvement which consists in adding 15 thereto ammonia in amounts sufficient to render the Ipotash sulfate insoluble, and pree iron aluminium and manganese in the mixtureas hydroxids.

In testimony, that'I claim theforegoing as 20 my invention, I have signed my name in presence of two Witnesses, this fifteenth day of October, 1906. y

I WALTER E. WADMANQ Witnesses: i i w v T. A. SIMONS, W. 0. SMITH. 

